Author Topic: Flat battery  (Read 557 times)

culzean

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Re: Flat battery
« Reply #15 on: May 14, 2020, 12:05:53 PM »
Had a 15-mile trip today and monitored the battery voltage. On startup it indicated 14.6 volts then after a couple of miles, it setted back to 12.7 volts. Then every two or three minutes it would cycle back to 14.6 before returning to 12.7 volts a minute later. One time it dropped back to 12.7 volts, so I switched on the rear screen heater, and it immediately increased to 14.6 volts. As soon as I switched the heater off, it returned to 12.7 volts. This voltage cycling indicates to me the ECU seeing the increased load and adjusting the charging rate accordingly.

Good job,  that is what you would expect the electrical load detector ( ELD ) to be there for,  it is proper counter-intuitive to have to increase the load by turning equipment on to increase the battery charging though..  I watched the 4  LED lamps on my cigarette lighter expansion sockets and noticed the top two would go off for a while and then come back on - showing that alternator voltage was changing.

I was shocked when I fitted a new almost fully charged Li-Ion battery to my Phillips shaver ( soldered in ) and the shaver only lasted a few shaves before red lights flashed and it stopped - charging it had no effect -  I checked battery voltage and it was fine - but the shaver said NO !  I had to unsolder one end of battery and connect a 5 watt light bulb across it and monitor the voltage until it dropper to 'minimum voltage'  - then connected battery back and charged it - it has been fine ever since - the shaver was using 'coulomb counting' to check what was going in and out of battery and because battery was charged when I fitted it and the circuit saw nothing going in it stopped shaver even though battery was full.

looks like same coulomb counting system on the 'stop-start' jazz battery - which is why negative charger clip needs to go on an earth point and not battery terminal because clipping to terminal bypasses the charging sensor..
« Last Edit: May 14, 2020, 05:21:26 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

madasafish

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Re: Flat battery
« Reply #16 on: May 14, 2020, 12:47:28 PM »
The battery in my Jazz is now just over 8 years old.

I have been pushing the car out of the garage (downhill) daily to work in it making bits for beekeeping. And driving it back in again - uphill - when finshed.

After three days teh battery complained. Starter turnover was poor.

Charged it and tested battery voltage: 12.1V. Marginal.

As winter is coming .. and the demand for new batteries will surely increase as lockdown ends - I ordered a new Yuasa one from the links posted before..
Many thanks...

Jocko

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Re: Flat battery
« Reply #17 on: May 14, 2020, 01:59:01 PM »
Yes, as I said on another post today, 40% of the AA's call outs, yesterday, was for flat batteries.

culzean

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Re: Flat battery
« Reply #18 on: June 10, 2020, 12:06:41 PM »
Here is a reasonably priced double USB charger with voltage and current readout ( reads voltage when no USB device plugged in and display flips between USB charging current and system voltage when something plugged in ).

https://www.amazon.co.uk/Dual-USB-Car-Charger-Built/dp/B01N5I0J92/ref=pd_rhf_ee_s_bmx_0_10?_encoding=UTF8&pd_rd_i=B01N5I0J92&pd_rd_r=d1bc9f54-2af8-4e19-adb2-5b6ea52b68b0&pd_rd_w=qfs4V&pd_rd_wg=mEhoL&pf_rd_p=4416d6a2-fd8f-40d0-816e-4414687de4d4&pf_rd_r=X467XRQQXD87571DVT92&psc=1&refRID=X467XRQQXD87571DVT92
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

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